When Cannabis Use Masks a Rare But Treatable Diagnosis: A Case of Acute Intermittent Porphyria in an Adolescent
A 15-year-old girl's nausea, vomiting, and weight loss were initially attributed to cannabis use and disordered eating — but her true diagnosis was acute intermittent porphyria, a rare metabolic condition that was nearly missed.
Quick Facts
What This Study Found
This case report describes a diagnostic near-miss that highlights an important clinical lesson: when a patient's symptoms overlap with known cannabis effects, the cannabis use can become a cognitive shortcut that prevents clinicians from looking further.
A 15-year-old girl presented to the emergency department with nausea, vomiting, and decreased appetite. She used cannabis and had disordered eating behaviors — two conditions that easily explain her symptoms. She was discharged. The next day, she returned with seizures and altered mental status.
The workup revealed acute intermittent porphyria (AIP), a rare but highly treatable metabolic disorder caused by a deficiency in the enzyme porphobilinogen deaminase. AIP produces episodic symptoms — abdominal pain, nausea, vomiting, neuropsychiatric changes, seizures — that overlap significantly with both cannabinoid hyperemesis syndrome (CHS) and eating disorders.
The key clinical lesson is about attribution bias. Cannabis use provided a ready explanation for the symptoms (CHS), and disordered eating provided another. Both were real — the patient did use cannabis and did have disordered eating. But neither was the primary cause of her acute presentation. The AIP diagnosis required a high index of suspicion and specific laboratory testing that wasn't performed on the first visit.
The case is the first in the literature to discuss the diagnostic overlap between CHS and AIP, filling an important gap for emergency physicians and pediatricians who increasingly encounter adolescent cannabis users with GI complaints.
Key Numbers
1 patient, 15-year-old female. Initial presentation: nausea, vomiting, decreased appetite. Cannabis use and disordered eating present. Discharged from ED. Returned next day: seizures, altered mental status. Diagnosis: acute intermittent porphyria. Treated with appropriate AIP management and responded well.
How They Did This
Single case report of a 15-year-old female presenting with nausea, vomiting, decreased appetite, cannabis use, and disordered eating. Initially discharged from the ED, returned the next day with seizures and altered mental status. Medical workup revealed acute intermittent porphyria. Treated appropriately with recovery.
Why This Research Matters
As cannabis use increases among adolescents, clinicians are becoming more familiar with cannabinoid hyperemesis syndrome — and that familiarity creates a diagnostic trap. When a young cannabis user presents with cyclical vomiting, CHS is a tempting diagnosis. But this case demonstrates that cannabis use doesn't immunize against other diagnoses, and attributing symptoms to cannabis without ruling out other causes can delay treatment for serious conditions.
The Bigger Picture
This case report adds a diagnostic caution to the clinical cannabis literature. While most studies in the database examine what cannabis does to the body, this case examines what cannabis as a diagnostic label does to clinical reasoning. The growing recognition of CHS (cyclical vomiting in cannabis users) is valuable, but it can become a diagnostic anchor that prevents consideration of other causes — a cognitive bias problem, not a pharmacological one.
What This Study Doesn't Tell Us
Single case report — the lowest level of clinical evidence. AIP is genuinely rare (estimated 1 in 20,000), so this diagnostic confusion will be uncommon. The case doesn't establish that cannabis-AIP misdiagnosis is frequent, only that it's possible. The patient's cannabis use and disordered eating were real comorbidities, making the diagnostic challenge genuinely complex.
Questions This Raises
- ?How often are serious medical conditions initially misattributed to cannabis use in adolescents?
- ?Should emergency departments have a protocol for red flags that distinguish CHS from other causes of cyclical vomiting?
- ?Does cannabis use itself affect porphyria episodes (there's speculation about endocannabinoid-porphyrin pathway interactions)?
- ?Are other rare metabolic conditions similarly at risk of being masked by cannabis use diagnoses?
Trust & Context
- Key Stat:
- Evidence Grade:
- Single case report — the most preliminary level of clinical evidence. Valuable as a diagnostic teaching case and the first to describe CHS-AIP overlap, but a single patient cannot establish the frequency or broader implications of this diagnostic confusion.
- Study Age:
- Published in 2025. Cannabinoid hyperemesis syndrome recognition has increased dramatically in recent years, making this diagnostic trap increasingly relevant.
- Original Title:
- An Adolescent Female With Disordered Eating and Cannabis Use Found to Have Acute Intermittent Porphyria.
- Published In:
- Case reports in psychiatry, 2025, 8875138 (2025) — Case Reports in Psychiatry publishes detailed case studies in the field of psychiatry.
- Authors:
- Gertz, Brooke, Mullen, Mark, Pesavento, Tony
- Database ID:
- RTHC-06528
Evidence Hierarchy
Describes what happened to one person or a small group.
What do these levels mean? →Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-06528APA
Gertz, Brooke; Mullen, Mark; Pesavento, Tony. (2025). An Adolescent Female With Disordered Eating and Cannabis Use Found to Have Acute Intermittent Porphyria.. Case reports in psychiatry, 2025, 8875138. https://doi.org/10.1155/crps/8875138
MLA
Gertz, Brooke, et al. "An Adolescent Female With Disordered Eating and Cannabis Use Found to Have Acute Intermittent Porphyria.." Case reports in psychiatry, 2025. https://doi.org/10.1155/crps/8875138
RethinkTHC
RethinkTHC Research Database. "An Adolescent Female With Disordered Eating and Cannabis Use..." RTHC-06528. Retrieved from https://rethinkthc.com/research/gertz-2025-an-adolescent-female-with
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.